Heavy is not necessarily bad. Depends on what you want from the board. For a permance board long or short which you want to throw around more and for late take-offs and steep waves you want your board to be as light as possibile. However for weaker less steep waves a heavier board is more likely to make sections as it has the momentum and will glide much better. Nose riders and some retro fish are glassed heavy for this reason. Of course with weight comes the added fun of being dragged by it when you wipe out though.
KS